The present disclosure relates to an apparatus for use in continuous cyclical processes employing fluidized solid techniques, such as a hydrocarbon fluid catalytic cracking (FCC) process, and is particularly directed to an injector module for introducing feedstocks into a reactor vessel for carrying out FCC processes.
Fluid catalytic cracking (FCC) processes are used in the refining of petroleum for producing various products such as low boiling point hydrocarbon products, especially gasoline, from relatively higher boiling feeds, or feedstocks. There are two pathways for the feed to crack into gaseous hydrocarbons, i.e., catalytic and thermal. Thermal cracking in a FCC reactor is generally undesirable as this type of cracking can result in the generation of light gases such as methane in addition to coke.
Various approaches have been adapted to rapidly break up the fluid feedstock vaporization. One approach involves the spraying of feedstock oil against a bolt head under pressure to fracture the feedstock. Steam is then used to carry the fractured particles out through a nozzle into the catalyst flow of the riser section of the FCC reactor. With this approach hydrocarbon feedstock is directed in a substantially perpendicular direction to the flowing stream of catalyst particles and onto a central strike surface on a target cylinder for disbursing the mixture of hydrocarbons and catalyst particles within the FCC reactor. Another approach uses steam flowing into a chamber with the feedstock oil, with the two flows of particles mixing and then flowing through an orifice, or a restricting nozzle, to atomize the mixed fluid. A third approach uses a twisting or spiral shaped nozzle to fracture the feedstock oil, with steam then added to carry the feedstock oil into the path of the catalyst.
In all of these installations, the feed injection nozzles and their mounting arrangements have various known issues. For example, the feed injection nozzles are subject to erosion and are easily and quickly degraded by the chemically-active catalysts. The nozzle arrangements are sometimes installed at different levels within the riser, with typically 4 to 12 nozzles at each level. Each nozzle projects onto the riser pipe wall and through the refractory lining on the inside of the riser pipe, with each of the nozzles having piping attached thereto for the delivery of feedstock and steam, and sometimes this piping includes drains or “rod out” ports. This nozzle and piping arrangement is very complex, requiring isolation valves and support piping, is very large in size, and is expensive.
If a first nozzle fails in a typical arrangement, a second oppositely positioned nozzle sprays high velocity fuel with catalyst onto the opposite side of the riser where the first failed nozzle is located, causing erosive or corrosive problems with the refractory lining and/or wall of the riser. This can cause catastrophic failure of the FCC process and dangerous operating conditions for plant personnel. Excessive heating of a nozzle assembly located on the riser is a dangerous condition for plant personnel who can be easily injured if required to operate a valve or perform other operational or maintenance functions on or near the riser. Nozzles can be very expensive, as is the cost to install a replacement nozzle in a riser. One of the reasons for this high cost is that the piping attached to each nozzle must match in position and orientation and must be properly positioned for connection to a nozzle in a very restrictive space involving complex piping. Typically there are 4 or 6 nozzles incorporated, and as you get bigger units, sometimes there is 8 or 10 nozzles, but in general there are no more than 10. There appears to be only one assembly in the world that has up to 14 nozzles in it.
Thus, there is a need for a FCC processing module that is durable and easily maintainable.